1. Field of Invention
The present invention relates generally to laser scanning bar code symbol reading systems, and more particularly to portable bar code symbol reading systems capable of generating raster-type laser scanning patterns having variable speed and resolution for reading various types of 1-D and 2-D bar code symbols during hands-on and hands-free modes of operation.
2. Brief Description of the Prior Art
Bar code symbols have become widely used in many commercial environments such as, for example, point-of-sale (POS) stations in retail stores and supermarkets, inventory and document tracking, and diverse data control applications. To meet the growing demands of this recent technological innovation, bar code symbol readers of various types have been developed for scanning and decoding bar code symbol patterns and producing symbol character data for use as input in automated data processing systems.
In general, laser scanning bar code symbol scanners are used for reading one-dimensional (1D) and two-dimensional (2-D) bar code symbols on products and packages for identification purposes. 2-D bar code symbols are advantageous in that they have the capacity to encode a substantially larger volume of data than 1D bar code symbols. Consequently, 2-D bar code symbols have enjoyed increasing popularity over recent years.
Many different techniques exist for scanning laser beams across objects bearing 2-D bar code symbols. Examples of 2-D laser scanning mechanisms for reading 2-D bar code symbols (e.g. the popular PDF 417 symbology) are described in U.S. Pat. Nos. 5,665,954, 5,691,834, and 5,550,367 and EPO Patent Application Publication No. EP 0 731 417 A2, incorporated herein by reference.
While each of these prior art laser scanning mechanisms are capable of producing a raster-type laser scanning pattern, such prior art techniques are unnecessarily complicated, expensive to manufacture, and generally do not enable precise speed/resolution control within the raster scanning pattern in a simple and practical manner required by numerous 2-D scanning applications.
Thus, there is a great need in the bar code symbol reading art for a bar code symbol reading system and method which overcomes the above-described shortcomings and drawbacks without compromising system performance and versatility.
Accordingly, it is a primary object of the present invention to provide improved laser scanning bar code symbol reading system that avoids the shortcomings and drawbacks of prior art methods and technologies.
A further object of the present invention is to provide a bar code symbol reading system comprising a hand-supportable bar code symbol reading device which embodies an electronically-controlled bar code symbol reading engine for producing a raster-type laser scanning pattern in either a hands-free or hands-on mode of operation for scanning 1-D and 2D bar code symbols.
Another object of the present invention is to provide such a bar code symbol reading system, wherein a support stand is provided for supporting the hand-supportable bar code symbol reading device above a counter-top or like surface during the hands-free mode of operation.
Another object of the present invention is to provide such a bar code symbol reading system, wherein the hand-supportable bar code symbol reading device can be used as either a portable automatic hand-supported bar code symbol reader in its hands-on mode of operation, or as an automatic fixed projection-type bar code symbol reader in its hands-free mode of operation.
Another object of the present invention is to provide such a bar code symbol reading system, wherein the electronically-controlled bar code symbol reading engine has (i) a high-speed/high-resolution raster scanning mode of operation during which a high-speed, high-resolution raster-type scanning pattern is precisely generated under electronic control, and (ii) a high-speed/low-resolution raster scanning mode of operation during which a high-speed, low-resolution raster-type scanning pattern is precisely generated under electronic control.
Another object of the present invention is to provide such a bar code symbol reading system, wherein the electronically-controlled bar code symbol reading engine is induced into its high-speed/high-resolution raster scanning mode of operation when the hand-supportable bar code symbol reading device is removed from its support stand, and into its high-speed/low-resolution raster scanning mode when the hand-supportable bar code symbol reading device is placed into its support stand.
Another object of the present invention is to provide such a bar code symbol reading system, wherein 2-D bar code symbols can be easily and reliably read in the hands-on mode of operation when the electronically-controlled bar code symbol reading engine is induced into its high-speed/high-resolution raster scanning mode of operation.
Another object of the present invention is to provide such a bar code symbol reading system, wherein 2-D bar code symbols can be easily and reliably read in the hands-free mode of operation when the electronically-controlled bar code symbol reading engine is induced into its high-speed/low-resolution raster scanning mode of operation as, for example, during sheet reading applications.
Another object of the present invention is to provide such a bar code symbol reading system, wherein 2-D bar code symbols, containing numerous lines of information encoded in accordance with the PDF 147 symbology, can be read by the bar code symbol reading device and the symbol character data representative thereof be automatically transmitted to a base unit over a one-way wireless radio-frequency (RF) link, and therefrom, onto a host computer, whereupon the base unit an acoustical acknowledgment signal is automatically generated for reception by the human operator.
Another object of the present invention is to provide such a bar code symbol reading system, wherein the hand-supportable bar code symbol reading device is provided with an IR-based object detection subsystem for enabling automatic actuation of the raster-type bar code symbol reading engine of the present invention upon automatic detection of objects.
Another object of the present invention is to provide such a bar code symbol reading system, wherein the hand-supportable bar code symbol reading device is provided with a manually-actuated trigger for enabling manual actuation of the raster-type bar code symbol reading engine of the present invention.
Another object of the present invention is to provide such a bar code symbol reading system, wherein the raster-type bar code symbol reading engine of the present invention can be electronically-reconfigured to produce a single-line type laser scanning pattern upon manual actuation of an external switch provided on the exterior of the hand-supportable housing of the bar code symbol reading device, or upon reading a predesigned mode-switching bar code symbol, for reading 1-D bar code symbols.
A further object of the present invention is to provide such a bar code symbol reading system, wherein the raster-type bar code symbol reading engine comprises a pair of mechanically-damped off-resonant laser beam scanning mechanisms that are arranged on a miniature optical bench and electronically-controlled by a synchronously driven drive circuit.
A further object of the present invention is to provide such a bar code symbol reading system, wherein the raster-type bar code symbol reading engine comprises a pair of mechanically-damped off-resonant laser beam scanning mechanisms that are arranged on a miniature optical bench and electronically-controlled by an asynchronously driven drive circuit so that the raster laser scanning pattern floats slightly along the y-scanning direction to facilitate reading of 2-D bar code symbols during the hands-on mode of operation.
A further object of the present invention is to provide such a bar code symbol reading system, wherein each such laser beam scanning mechanism comprises an etched scanning element having a small flexible gap region of closely-controlled dimensions disposed between an anchored base portion and a laser beam deflecting portion.
Another object of the present invention is to provide such a bar code symbol reading system, wherein the resonant frequency or oscillation of each laser beam deflecting portion relative to the anchored base portion is determined by the closely controlled dimensions of the flexible gap region set during manufacture.
A further object of the present invention is to provide such a bar code symbol reading system, wherein the resonant frequency of oscillation of each scanning element is tuned by adjusting the thickness and width of the flexible gap region.
Another object of the present invention is to provide such a bar code symbol reading system, wherein the physical dimensions of the flexible gap region are closely controlled by using chemical-etching techniques during manufacture.
Another object of the present invention is to provide such a bar code symbol reading system, wherein each etched scanning element is manufactured by chemically etching a double-sided copper clad sheet consisting of a polyamide base material laminated between ultra-thin cooper sheets.
Another object of the present invention is to provide such a bar code symbol reading system, wherein a permanent magnet is mounted on the rear surface of each laser beam deflecting portion, and a laser beam deflecting element is mounted on the front surface of the laser beam deflecting portion.
Another object of the present invention is to provide such a bar code symbol reading to system, wherein the base portion of each scanning element is securely fixed to an optical bench and the laser beam deflecting portion is forced to oscillate substantially away from the natural resonant frequency of the scanning element, by a reversible electromagnet disposed in close proximity to a permanent magnet mounted to the rear surface of the laser beam deflecting portion.
Another object of the present invention is to provide such a bar code symbol reading system, wherein the natural harmonic (i.e., resonant) frequency of each laser beam deflecting portion about the anchored base portion is mechanically-damped by adding a thin layer of flexible rubber material to the gap region of the scanning element during manufacture, and the laser beam deflecting portion is forcibly driven by a reversible electromagnet operated at a forcing (i.e., driving) frequency tuned substantially away (i.e., off) from the natural resonant frequency of the laser beam deflecting portion.
Another object of the present invention is to provide such a bar code symbol reading system, wherein the steady-state frequency of oscillation of the laser beam deflecting portion is determined by the frequency of polarity reversal of the electromagnet, which is electronically controlled by the polarity of electrical current supplied to the input terminals of the magnet coil of the reversible electromagnet.
Another object of the present invention is to provide such a bar code symbol reading system with an electronically-controlled laser beam scanning mechanism, wherein the driving or forcing frequency of the electromagnet thereof is selected to be at least ten percent off (i.e., greater or less than) the natural resonant frequency of the laser beam deflecting portion.
Another object of the present invention is to provide such a bar code symbol reading system, wherein the steady-state frequency of oscillation can be set at the time of manufacture to be any one of a very large range of values (e.g., 50-500 Hz) for use in both low-speed and high-speed laser scanning systems.
Another object of the present invention is to provide such a bar code symbol reading system, wherein the laser beam scanning mechanism has ultra-low power consumption, and a low operating current.
Another object of the present invention is to provide such a bar code symbol reading system, wherein the angular sweep of each laser beam deflecting element is at about thirty (i.e., +/xe2x88x9215 degrees) measured with respect to the point of pivot about the anchored base portion of the scanning element of the present invention.
Another object of the present invention is to provide such a bar code symbol reading system, wherein the scanning element and electromagnet are mounted within an ultra-compact housing having integrated stops for delimiting the sweep that the scanning element is permitted to undergo during operation.
A further object of the present invention is to provide such a system with one or more automatic (i.e., triggerless) hand-supportable laser-based bar code symbol reading devices, each of which is capable of automatically transmitting data packets to its base unit after each successful reading of a bar code symbol.
A further object of the present invention is to provide such a bar code symbol system, wherein the base unit is adapted to support the hand-supportable bar code symbol reading device in its automatic hands-free mode of operation.
Another object of the present invention is to provide an improved bar code symbol reading system capable of generating high-speed raster-type laser scanning patterns for reading one-dimensional and two-dimensional bar code symbols in both hands-on and hands-off modes of operation.
A further object of the present invention is to provide such a bar code symbol reading system in the form of a portable data (transaction) terminal capable of producing either a 1-D or 2-D laser scanning pattern by manual selection, or bar code symbol programming, for reading 1-D or 2-D bar code symbols, respectively.
A further object of the present invention is to provide such a bar code symbol reading system in the form of a body-wearable transaction terminal capable of producing either a 1-D or 2-D laser scanning pattern for reading 1-D or 2-D bar code symbols, respectively.
A further object of the present invention is to provide such a bar code symbol reading system, wherein the base unit contains a battery recharging device that automatically recharges batteries contained in the hand-supportable device when the hand-supportable device is supported within the base unit.
It is another object of the present invention to provide such a bar code symbol reading system with a mode of operation that permits the user to automatically read one or more bar code symbols on an object in a consecutive manner.
A further object of the present invention is to provide such a bar code symbol reading system, wherein a plurality of automatic hand-supportable bar code symbol reading devices are used in conjunction with a plurality of base units, each of which is mated to a particular bar code symbol reading device.
A further object is to provide such a bar code symbol reading device, wherein the automatic hand-supportable bar code (symbol) reading device has an infrared (IR) based object detection field which spatially encompasses at least a portion of its visible laser light scan field along the operative scanning range of the device, thereby improving the laser beam pointing efficiency of the device during the automatic bar code reading process of the present invention.
Another object of the present invention is to provide such an bar code symbol reading system, wherein the base unit has a support frame that supports the hand-supportable housing of the device in a selected mounting position, and permits complete gripping of the handle portion of the hand-supportable housing prior to removing it from the support frame.
A further object of the present invention is to provide such an automatic bar code symbol reading system, wherein the hand-supportable bar code reading device has a hands-on high-speed/high-resolution mode of raster scanning, and a hands-off high-speed/low-resolution mode of raster scanning.
An even further object of the present invention is to provide an automatic hand-supportable bar code reading device which prevents multiple reading of the same bar code symbol due to the dwelling of the laser scanning beam upon a bar code symbol for an extended period of time.
It is a further object of the present invention to provide an automatic hand-supportable bar code reading device having a control system which has a finite number of states through which the device may pass during its automatic operation, in response to diverse conditions automatically detected within the object detection and scan fields of the device.
It is yet a further object of the present invention to provide a portable, fully automatic bar code symbol reading system which is compact, simple to use and versatile.
Yet a further object of the present invention is to provide a novel method of reading bar code symbols using the automatic hand-supportable laser scanning device of the present invention.
A further object of the present invention is to provide such a bar code symbol reading system, wherein the laser scanning plane thereof extends upwardly, downwardly, or laterally transverse to the pointing direction of the wearer""s hand on which the device is mounted.
A further object of the present invention is to provide a point-of-sale station incorporating the automatic bar code symbol reading system of the present invention.
These and further objects of the present invention will become apparent hereinafter and in the claims.